The present invention relates to a pointer for attachment to the digging arm of a mechanical excavator or digging machine, or to some other appropriate part of said machine.
Valuable assets are lost annually as a result of severing or destroying underground cables and underground conductors during ground excavating work carried out with the aid of excavating or digging machines. Hitherto, no effective method has been proposed which will enable the extension of underground cables, etc., to be detected and marked-out before commencing the excavation work. For instance, hitherto, the presence of an underground cable has been localized by detecting its magnetic field in accordance with standard methods and determining the position and the geometric extension of the cable on the basis thereof. The extension of the cable is then marked with the aid of pegs driven into the ground. In the case of cables which are not conducting or in the case of waterpipes or optical cables which are either surrounded by a metal screen or include an aluminium strip, the underground object has been detected with the aid of an active transmitter and receiver with the aid of overhead induction, whereafter the position of the cable or conduit is again marked with the aid of pegs driven into the ground.
One drawback is that the pegs become broken or are inadvertantly moved, or quite simply removed, causing uncertainty as to the actual position of the cable. The cable is often severed or dug up even when the pegs remain in position.
The object of the present invention is to provide a pointer which will constantly point to or indicate the location of an underground cable during an excavating operation, so that the machine operator can avoid cutting through or digging-up the cable or conduit.